withDefault(): Prevent “property of non-object” error

// BelongsTo Default Models
// Let's say you have Post belonging to Author and then Blade code:
$post->author->name;
 
// Of course, you can prevent it like this:
$post->author->name ?? ''
// or
@$post->author->name
 
// But you can do it on Eloquent relationship level:
// this relation will return an empty App\Author model if no author is attached to the post
public function author() {
    return $this->belongsTo(Author::class)->withDefault();
}
// or
public function author() {
    return $this->belongsTo(Author::class)->withDefault([
        'name' => 'Guest Author'
    ]);
}

Tip given by @coderahuljat